x  p pressure gastge



March 27, 1945. w, T, GORTON PRESSURE GAUGE Filed June 29, 1943 glwucwvbo'n Walter T- Burton axmwuka'm Patented Mar. 27, 1945 eanssuas GAUGE;

I Walter T; Gorton, Springfield;.Mass.

AnnlicatiorrJune 2.9; 194 Serial No.. 492,661 I 4 Claims... (01. 73 -35.)

(Granteds underthei. act of March 3, 1883, as amended April 3% 1.928;. 3.7a 0.6. r51)- I The invention. described. herein ail be man factured and used by or rorthe Government. fo

overnmental purposes, without, the. pay ent t me offany royalty thereon.

This invention relates to a. comparatlve pressure. gauge particularly for determining relative pressures developedby firearm cartridges;

The conventional crusher type pressure gauge for. determiningthe. maximum; pressures developed by firearm, cartridges. will. accurately measure. the maximum. intensity. of such. p ess r in pounds per square inch. For. general usage however such accuracy i usually not necessary- Furthermore;' the. crushe typ messure gauge i a costly" instrument. and. such cost. is, freq ently prohibitive. or. unwarranted. Therei'ore, inmost instances where occasional checks must be made on. ammunition. to. determine. whether the pressure. developed y the ammunition, is of correct order of. magnitude. a simple pressure gauge for omp rative results. would. be very desirable.

Accordingly, it. is an object. of this invention to. p ovide a. comparative pressure gauge for inlater, utilizes the conventional blowback principle commonly employed in many automatic firearms. By utilizing this principle a comparative pressure gauge can be easily and economically constructed. Such a gauge comprises a receiver, a bolt member slidably mounted within the receiver, and a barrel. The pressure gauge is preferably mounted with the barrel in a vertical po-. sition.

Relative breech pressures developed by the cartridge are then readily determined by indicating and observing the height to which the bolt member recoils after the discharge of the cartridge. The gauge may first be calibrated if desired by using ammunition having a known pressure.

threads 4.. The; receiver Ir is preierably of tubu. lar construction as shown. in Fig. 1 and defines, a vertical. channel; of sufficient len th to. accommodate the maximum recoil movement. of. bolt 3,. A

suitable. slot 5 is; provided in receiver I slightly above. the end of. barrelv 2. to facilitate loading a cartridge. 6. into the. chamber I otbarrel. 2. A long. longitudinal.slotv 8 is provided on receiver I totreceive a bolt. stud. 9. aswill be described.

The bolt 3 is of cylindrical construction and is provided with an integral firing pin or striker 20 onthe, face thereof. adjacent. the end of barrel 2.

The. bolt stud 8..is. inserted through slot Iiv in. receiver I. and. isscrewed. into a suitably threaded hole inv bolt 3.. Stud 9. is. provided for manually raising. the. bolt 3 within receiver I. A suitable notch. IQ is, provided at. the top of slot 8 tov hold bolt 3 in. a. raised, position. while loadin a cartridge into the. chamber. To record th distance the bolt. recoils. after. discharge of the cartridge a graduated, scale II. is'providedv on. the. surface of receiver I asshown. in Fig, 1. An indicator IZ- is secured to. bolt. stud 9,.td facilitate, reading the maximum recoil travel. of the, bolt- 3.

The pressure. gauge. i preferably mounted in. a vertical position as shown in Fig. 1. 'Aninverted U-shaped stand maybe utilized for such mounting which comprises twotubular uprights I3 joined at. their upper ends. by a crossarm, I4.

The crossarm', I4. may be secured. as. by welding to each' of the supports I3 and the supports I3 may be in turn secured to a suitable bench top I5 as by the flanges I6. A flange I1 secured as by welding to the underside of the arm I4 and in the center thereof is provided to receive the threaded end I8 of receiver I. A suitable hole I9 is provided in bench I5 thru which barrel 2 may be inserted so that receiver I may be screwed into flange I1. It is readily apparent that the pressure gauge may be readily removed for cleaning purposes by merely unscrewing from flange I'I.

It should be mentioned here that the cartridge in this particular application as shown in Fig. 1 is of the rim fire type and consequently the striker 20 is eccentric with respect to the longitudinal axis of bolt 3. For center flre cartridges striker. 20 will of course be formed on the axis of bolt 3. To insure uniform extraction of the cartridge case after discharge thereof, each case is first lubricated with a suitable light oil. To operate the pressure gauge the bolt 3 is raised to its uppermost position and bolt stud 9 rotated into engagement with notch I 0. Thus bolt 3 will be held at the top of receiver I. The lubricated cartridge 6 is then inserted in chamber I, care being exercised to be sure that the cartridge is fully seated. Bolt stud 9 is then. rotated slightly to the left a shown in Fig. 1 and released. The force of gravity will cause the bolt 3 to fall rapidly and striker 28 will hit the primer of the cartridge thereby effecting its discharge. The resulting gas pressure will blowback the cartridge 5 and hence drive thebolt 3 upwardly. The maximum rise of bolt 3 can then be readily determined by observing the position of indicator l2 on the graduated scale I I.

This pressure gauge may first be calibrated with standard cartridges of known pressure and the readings thus obtained may be used as a basis for determining whether cartridges of subsequent lots of cartridges conform to the standard pressure, Thus comparative pressure determinations may be conveniently made by the use of this pressure gauge.

While this type of pressure gauge is preferably used with cartridges developing comparatively w breech pressures it is obviously within the scope of this invention to adopt this device to cartridges developing comparatively high pressures such as developed by the U. S. Army caliber .30 cartridge. This may be readily accomplished by merely increasing the mass of the bolt and of course proportionately increasing the size of the other related components in order to accommodate the greatly increased pressure developed by such a high powered cartridge.

I claim:

1. A gauge for indicating pressure developed by a firearm cartridge comprising a vertically mounted barrel, said barrel being adapted to receive a cartridge, a receiver secured to the barrel, said receiver defining a vertical channel, an inertia member slidably mounted within said receiver channel and arranged to rest on the base of a cartridge inserted in said barrel, a firing pin associated with said inertia member and arranged to discharge the cartridge, and means for indicating the height reached by said inertia member after discharge of said cartridge, the mass of said inertia member being suflicient to limit its travel to less than the maximum permitted by the receiver.

2. A gauge for indicating pressure developed by a firearm cartridge comprisin a vertically mounted barrel, said barrel being adapted to receive a cartridge, a tubular receiver secured to the barrel, an inertia member slidably mounted within said receiver and arranged to rest on the base of a cartridge inserted in said barrel, a firing pin projection on the bottom of said inertia member arranged to discharge the cartridge by dropping the inertia member on the cartridge, and means for indicating the height reached by said inertia member after discharge of said cartridge, the mass of said inertia member being sufficient to limit its travel to less than the maximum per- ,-mitted by the receiver. 7

3. A gauge for indicating pressure developed by a firearm cartridge comprising a vertically mounted barrel, said barrel being adapted to receive a cartridge, a tubular receiver secured to the barrel, an inertia member slidably mounted within said receiver and arranged to rest on the base of a cartridge inserted in said barrel, means for latching said inertia member in said receiver in an elevated position with respect to the barrel, a firing pin projection on the base of said inertia member arranged to discharge the cartridge by the fall of said inertia member from its latched position, and means for indicating the height reached by said inertia member after discharge of said cartridge, the mass of said inertia member being sufiicient to limit its travel to less than the maximum permitted by the receiver.

4. A gauge for indicating pressure developed by a firearm cartridge comprising a vertically mounted barrel, said barrel being adapted to receive a cartridge, a tubular receiver secured to the barrel, an inertia member slidably mounted within said receiver and arranged to rest on the base of a cartridge inserted in said barrel, a vertically extending slot in said receiver, a substantially horizontal slot in said receiver at the top of said vertical slot, a projection on said inertia member arranged to move in said slots whereby said inertia member may be latched in an elevated position with respect to said barrel by entry of said projection in said horizontal slot, 2. firing pin projection in the base of said inertia member arranged to discharge the cartridge by the fall of said inertia member from its latched position, a height scale on said receiver disposed along said vertical slot, and a pointer on said projection cooperating with said scale to indicate the height reached by said inertia member after discharge of said cartridge.

WALTER T. GORTON. 

